System and method for managing a storage array

ABSTRACT

Systems and methods for managing a storage array are disclosed. A method may include segmenting each of a plurality of physical storage resources into a first storage area and a second storage area. The method may also include activating a first logical unit including each first storage area of the plurality of physical storage resources. The method may additionally include placing at least one designated physical resource of the plurality of physical storage resources in a powersave mode. The method may further include activating a second logical unit including the second storage areas of some of the plurality of physical storage resources but not the at least one designated physical storage resource. Moreover, the method may include storing data associated with a write operation intended for the at least one designated physical storage resource to the second logical unit.

TECHNICAL FIELD

The present disclosure relates in general to data storage, and moreparticularly to a system and method for managing a storage array.

BACKGROUND

As the value and use of information continues to increase, individualsand businesses seek additional ways to process and store information.One option available to users is information handling systems. Aninformation handling system generally processes, compiles, stores,and/or communicates information or data for business, personal, or otherpurposes thereby allowing users to take advantage of the value of theinformation. Because technology and information handling needs andrequirements vary between different users or applications, informationhandling systems may also vary regarding what information is handled,how the information is handled, how much information is processed,stored, or communicated, and how quickly and efficiently the informationmay be processed, stored, or communicated. The variations in informationhandling systems allow for information handling systems to be general orconfigured for a specific user or specific use such as financialtransaction processing, airline reservations, enterprise data storage,or global communications. In addition, information handling systems mayinclude a variety of hardware and software components that may beconfigured to process, store, and communicate information and mayinclude one or more computer systems, data storage systems, andnetworking systems.

Information handling systems often use an array of physical storageresources, such as a Redundant Array of Independent Disks (RAID), forexample, for storing information. Arrays of physical storage resourcestypically utilize multiple disks to perform input and output operationsand can be structured to provide redundancy which may increase faulttolerance. Other advantages of arrays of physical storage resources maybe increased data integrity, throughput and/or capacity. In operation,one or more physical storage resources disposed in an array of physicalstorage resources may appear to an operating system as a single logicalstorage unit or “logical unit.” Implementations of physical storageresource arrays can range from a few physical storage resources disposedin a server chassis, to hundreds of physical storage resources disposedin one or more separate storage enclosures.

However, one downside of redundant storage arrays is that they generallyrequire at least one physical storage resource within the storage arrayto serve as a redundant storage resource (e.g. for parity or mirroring).Thus, a redundant storage array typically consumes more power than anon-redundant storage array of similar storage capacity.

A traditional approach to reducing the power requirements of a redundantstorage array includes powering down or spinning down one of thephysical storage resources of the array. However, powering down one ofthe physical resources of a storage array may leave the storage array ina “degraded” state, whereby additional write operations to the arraycould become unrecoverable upon failure of one of the remainingpowered-on physical storage resources, thus negating the originalpurpose of implementing the redundant array.

SUMMARY

In accordance with the teachings of the present disclosure,disadvantages and problems associated with power management in aredundant storage array have been substantially reduced or eliminated.

In accordance with an embodiment of the present disclosure, a method formanaging a storage array is provided. The method may include segmentingeach of a plurality of physical storage resources into a first storagearea and a second storage area. The method may also include activating afirst logical unit including each first storage area of the plurality ofphysical storage resources. The method may additionally include placingat least one designated physical resource of the plurality of physicalstorage resources in a powersave mode. The method may further includeactivating a second logical unit including the second storage areas ofsome of the plurality of physical storage resources but not the at leastone designated physical storage resource. Moreover, the method mayinclude storing data associated with a write operation intended for theat least one designated physical storage resource to the second logicalunit.

In accordance with an embodiment of the present disclosure, a system formanaging a storage array may include a plurality of physical storageresources and a device communicatively coupled to the plurality ofstorage resources. The device may be configured to segment each of theplurality of physical storage resources into a first storage area and asecond storage area. The device may also be configured to activate afirst logical unit including each first storage area of the plurality ofphysical storage resources. The device may additionally be configured toplace at least one designated physical resource of the plurality ofphysical storage resources in a powersave mode. The device may furtherbe configured to activate a second logical unit including the secondstorage areas of some of the plurality of physical storage resources butnot the at least one designated physical storage resource. Moreover, thedevice may be configured to store data associated with a write operationintended for the at least one designated physical storage resource tothe second logical unit.

In accordance with an additional embodiment of the present disclosure, aa program of instructions may be embodied in a tangiblecomputer-readable medium. The program of instructions may be operableto, when executed: (a) segment each of a plurality of physical storageresources into a first storage area and a second storage area; (b)activate a first logical unit including each first storage area of theplurality of physical storage resources; (c) place at least onedesignated physical resource of the plurality of physical storageresources in a powersave mode; (d) activate a second logical unitincluding the second storage areas of some of the plurality of physicalstorage resources but not the at least one designated physical storageresources; and (e) store data associated with a write operation intendedfor the at least one designated physical storage resource to the secondlogical unit.

Other technical advantages will be apparent to those of ordinary skillin the art in view of the following specification, claims, and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present embodiments and advantagesthereof may be acquired by referring to the following description takenin conjunction with the accompanying drawings, in which like referencenumbers indicate like features, and wherein:

FIG. 1 illustrates a block diagram of an example system including aredundant storage array having enhanced power management features, inaccordance with the present disclosure;

FIG. 2 illustrates a flow chart of an example method for managing thepower consumption of a redundant storage array having enhanced powermanagement features, in accordance with the present disclosure; and

FIG. 3 illustrates a flow chart of an example method for updating aphysical storage resource in a storage array having enhanced powermanagement features, in accordance with the present disclosure.

DETAILED DESCRIPTION

Preferred embodiments and their advantages are best understood byreference to FIGS. 1 through 3, wherein like numbers are used toindicate like and corresponding parts.

For the purposes of this disclosure, an information handling system mayinclude any instrumentality or aggregate of instrumentalities operableto compute, classify, process, transmit, receive, retrieve, originate,switch, store, display, manifest, detect, record, reproduce, handle, orutilize any form of information, intelligence, or data for business,scientific, control, entertainment, or other purposes. For example, aninformation handling system may be a personal computer, a PDA, aconsumer electronic device, a network storage device, or any othersuitable device and may vary in size, shape, performance, functionality,and price. The information handling system may include memory, one ormore processing resources such as a central processing unit (CPU) orhardware or software control logic. Additional components or theinformation handling system may include one or more storage devices, oneor more communications ports for communicating with external devices aswell as various input and output (I/O) devices, such as a keyboard, amouse, and a video display. The information handling system may alsoinclude one or more buses operable to transmit communication between thevarious hardware components.

For the purposes of this disclosure, computer-readable media may includeany instrumentality or aggregation of instrumentalities that may retaindata and/or instructions for a period of time. Computer-readable mediamay include, without limitation, storage media such as a direct accessstorage device (e.g., a hard disk drive or floppy disk), a sequentialaccess storage device (e.g., a tape disk drive), compact disk, CD-ROM,DVD, random access memory (RAM), read-only memory (ROM), electricallyerasable programmable read-only memory (EEPROM), and/or flash memory, aswell as communications media such wires, optical fibers, microwaves,radio waves, and other electromagnetic and/or optical carriers; and/orany combination of the foregoing.

As discussed above, an information handling system may include or may becoupled via a network to an array of physical storage resources. Thearray of physical storage resources may include a plurality of physicalstorage resources, and may be operable to perform one or more inputand/or output storage operations, and/or may be structured to provideredundancy. In operation, one or more physical storage resourcesdisposed in an array of physical storage resources may appear to anoperating system as a single logical storage unit or “logical unit.”

In certain embodiments, an array of physical storage resources may beimplemented as a Redundant Array of Independent Disks (also referred toas a Redundant Array of Inexpensive Disks or a RAID). RAIDimplementations may employ a number of techniques to provide forredundancy, including striping, mirroring, and/or parity checking. Asknown in the art, RAIDs may be implemented according to numerous RAIDlevels, including without limitation, standard RAID levels (e.g., RAID0, RAID 1, RAID 3, RAID 4, RAID 5, and RAID 6), nested RAID levels(e.g., RAID 01, RAID 03, RAID 10, RAID 30, RAID 50, RAID 51, RAID 53,RAID 60, RAID 100), non-standard RAID levels, or others.

FIG. 1 illustrates a block diagram of an example system 100 includingredundant storage array 110 having enhanced power management features,in accordance with the present disclosure. As depicted in FIG. 1, system100 may include a node 102, a network 108, a controller 109, and astorage array 110.

Node 102 may comprise an information handling system and may generallybe operable to read data from and/or write data to one of more physicalstorage resources 112 of storage array 110. In certain embodiments, node102 may be a server. In other embodiments, node 102 may be a personalcomputer (e.g., a desktop or portable computer). As depicted in FIG. 1,node 102 may include a processor 103, a memory 104 communicativelycoupled to processor 103, and a network interface 106 coupled toprocessor 103.

Processor 103 may comprise any system, device, or apparatus operable tointerpret and/or execute program instructions and/or process data, andmay include, without limitation a microprocessor, microcontroller,digital signal processor (DSP), application specific integrated circuit(ASIC), or any other digital or analog circuitry configured to interpretand/or execute program instructions and/or process data. In someembodiments, processor 103 may interpret and/or execute programinstructions and/or process data stored in memory 104 and/or anothercomponent of node 102.

Memory 104 may be communicatively coupled to processor 103 and maycomprise any system, device, or apparatus operable to retain programinstructions or data for a period of time. Memory 104 may compriserandom access memory (RAM), electrically erasable programmable read-onlymemory (EEPROM), a PCMCIA card, flash memory, magnetic storage,opto-magnetic storage, or any suitable selection and/or array ofvolatile or non-volatile memory that retains data after power to node102 is turned off.

Network interface 106 may be any suitable system, apparatus, or deviceoperable to serve as an interface between node 102 and network 108.Network interface 106 may enable node 102 to communicate via network 108using any suitable transmission protocol and/or standard, includingwithout limitation all transmission protocols and/or standardsenumerated below with respect to the discussion of network 108.

Although system 100 is depicted as having one node 102, system 100 mayhave any number of nodes 102.

Network 108 may be a network and/or fabric configured to communicativelycouple node 102 to storage array 110. In certain embodiments, network108 may allow node 102 to couple physical storage resources 112 suchthat the physical storage resources 112 and/or logical units comprisingphysical storage resources 112 appear to node 102 as locally-attachedstorage resources. In the same or alternative embodiments, network 108may include a communication infrastructure, which provides physicalconnections, and a management layer, which organizes the physicalconnections between network 108, network interface 106 and storage array100. In the same or alternative embodiments, network 108 may allow blockI/O services and/or file access services to physical storage resources112 disposed in storage array 110.

Network 108 may be implemented as, or may be a part of, a storage areanetwork (SAN), personal area network (PAN), local area network (LAN), ametropolitan area network (MAN), a wide area network (WAN), a wirelesslocal area network (WLAN), a virtual private network (VPN), an intranet,the Internet or any other appropriate architecture or system thatfacilitates the communication of signals, data and/or messages(generally referred to as data). Network 108 may transmit data using anycommunication protocol, including without limitation, Frame Relay,Asynchronous Transfer Mode (ATM), Internet protocol (IP), otherpacket-based protocol, small computer system interface (SCSI), advancedtechnology attachment (ATA), serial ATA (SATA), advanced technologyattachment packet interface (ATAPI), serial storage architecture (SSA),integrated drive electronics (IDE), and/or any combination thereof.Further, network 108 may transport data using any storage protocol,including without limitation, Fibre Channel, Internet SCSI (iSCSI),Serial Attached SCSI (SAS), or any other storage transport compatiblewith SCSI protocol. Network 108 and its various components may beimplemented using hardware, software, or any combination thereof.

Controller 109 may be any suitable system, device, or apparatus thatmanages physical storage resources 112 of storage array 110 and/orpresents them to node 102 as logical units and/or virtual storageresources (e.g., a RAID controller). For example, if a RAID implementedusing the physical storage resources 112 of storage array 110,controller 109 may control how stored data is mirrored and/or stripedamong physical storage resources 112, and may present such RAID as asingle logical unit or virtual storage resource to node 102. In someexample embodiments, controller 109 may be an integral part of a storageenclosure housing one or more of physical storage resources 112. Inother example embodiments, controller may be an integral part of node102.

As depicted in FIG. 1, storage array 110 may include one or morephysical storage resources 112, and may be communicatively coupled tonode 102 and/or network 108, in order to facilitate communication ofdata between node 102 and physical storage resources 112. Physicalstorage resources 112 may include hard disk drives, magnetic tapelibraries, optical disk drives, magneto-optical disk drives, compactdisk drives, compact disk arrays, disk array controllers, and/or anycomputer-readable medium operable to store data.

As shown in FIG. 1, each physical storage resource 112 may be segmentedinto (a) a first storage area referred to herein as an array volume dataspace 114 and (b) a second storage area referred to herein as a journalspace 116. For example, each physical storage resource 112 may bepartitioned to create array volume data space 114 and journal space 116.As shown in FIG. 1, and as described in greater detail below withrespect to FIGS. 2 and 3, a data space logical unit 118 may be activatedto include one or more array volume data spaces 114. In certainembodiments, data space logical unit 118 may appear to an operatingsystem executing on node 102 as a single logical storage unit or virtualresource. Thus, node 102 may “see” data space logical unit 118 insteadof seeing each individual physical storage resource 112. In suchembodiments, data to be written to and/or read from storage array 110may be respectively written to and/or read from data space logical unit118.

Also, as shown in FIG. 1, and as described in greater detail below withrespect to FIGS. 2 and 3, a journal space logical unit 120 may includejournal spaces 116 of some but not all (e.g., all but one) of physicalstorage resources 112. However, unlike data space logical unit 118,journal space logical unit 120 may not be presented to or “seen” by node102 as a logical unit in certain embodiments of this disclosure.Instead, information and/or data associated with one or more physicalstorage resources 112 in a powersave mode may be written to and/or readfrom journal space logical unit 120 by controller 109, as described ingreater detail below with respect to FIGS. 2 and 3.

Although the embodiment shown in FIG. 1 depicts storage array 110 havingfive physical storage resources 112, storage array 210 may have anynumber of physical storage resources 112. In certain embodiments, system100 may include a storage enclosure to hold and power controller 109and/or one or more physical storage resources 112.

Although FIG. 1 depicts that node 102 is communicatively coupled tostorage array 110 via network 108, node 102 may be communicativelycoupled to one or more physical storage resources 112 without the needof network 108 or another similar network. For example, in certainembodiments, one or more physical storage resources 112 may be directlycoupled and/or locally attached to one or more nodes 102.

FIG. 2 illustrates a flow chart of an example method 200 for managingthe power consumption of redundant storage array 110, in accordance withthe present disclosure. According to one embodiment, method 200preferably begins at step 202. As noted above, teachings of the presentdisclosure may be implemented in a variety of configurations of system100. As such, the preferred initialization point for method 200 and theorder of the steps 202-212 comprising method 200 may depend on theimplementation chosen.

At step 202, node 102, controller 109, and/or another suitable componentof system 100 may segment each physical storage resource 112 into anarray volume data space 114 and a journal space 116. For example, eachphysical resource 112 may be segmented by creating separate partitionsfor each of its respective array volume data space 114 and journal space116. In certain embodiments, the journal space 116 may be implementedusing inner disk tracks of each of physical storage resource 112. Therelative sizes of each array volume data space 114 and journal space 116may be selected in any suitable manner. For example, the relative sizesmay be pre-determined by a manufacturer, a network administrator,information technology technician, and/or another user. In someembodiments, each array volume data space 114 may be of approximatelyidentical size. The same or alternative embodiments, each journal space116 may be of approximately identical size.

At step 204, controller 109 may activate data space logical unit 118including array volume data spaces 114. Data space logical unit 118 maybe a redundant storage array, and may be implemented using any suitableRAID level. Once activated, data space logical unit 118 may be presentedto or “seen” by node 102 as a single logical unit. Accordingly, data tobe written and/or read by node 102 by be written and/or read to dataspace logical unit 118.

At step 206, node 102, controller 109, and/or another suitable componentof system 100 may identify one or more physical storage resources 112 tobe placed in a powersave mode. The physical storage resource(s) 112 tobe placed in the powersave mode may be identified in any suitablemanner. For example, the physical storage resources(s) 112 to be placedin a powersave mode may be identified according to an established policyand/or algorithm (e.g., based on a program and/or logic resident on node102 and/or controller 109) that determines when to place one or morephysical storage resource(s) 112 in powersave mode.

At step 208, node 102, controller 109, and/or another suitable componentof system 100 may activate journal space logical unit 120 includingthose journal spaces 116 b-e of physical storage resources 112 b-e otherthan the identified physical storage resource(s) 112 (e.g., physicalstorage resource 112 a). Journal space logical unit 120 may be aredundant storage array, and may be implemented using any suitable RAIDlevel. In certain embodiments, journal space logical unit 120 may employa RAID level different than that of data space logical unit 118. Forexample, data space logical unit 118 may employ RAID 5, while journalspace logical unit 120 employs RAID 10. In certain embodiments, journalspace logical unit 120 may not be presented to or “seen” by node 102 asa logical unit. Instead, journal space logical unit 120 may be used tojournal or catalog write operations intended for physical storageresource 112 a while physical storage 112 a is in powersave mode, asdescribed in further detail below.

At step 210, node 102, controller 109, and/or another suitable componentof system 100 may place the identified physical storage resource(s) 112in a powersave mode. A powersave mode may include any mode and/or stateof a physical storage resource 112 in which it may consume less powerthan if it were operating in a normal mode. For example, placing aphysical storage resource 112 in a powersave mode may include spinningit down, placing it in a lower power “standby” or “sleep” state, orremoving power from it entirely. For clarity, the remaining discussionof FIG. 2 and FIG. 3 assumes that physical storage resource 112 a is theidentified physical storage resource that is placed in a powersave mode.However, it is understood that any combination of physical storageresources 112 a-112 e may be placed in a powersave mode at steps 206-210in accordance with this disclosure.

At step 212, controller 109 and/or another suitable component of system100 may store all writes intended for the powered-down physical storagenode 112 a to the journal space logical unit 120. In certainembodiments, writes to journal space logical unit 120 may include a“journaled” write, wherein information regarding the destination of awrite may also be written in addition to the data to be written. Forexample, writes to journal space logical unit 120 may includeinformation regarding the destination sector, track, and/or block of thepowered-down physical storage node 112 a corresponding to data writtento journal space logical unit 120. In addition, writes to journal spacelogical unit 120 may include information regarding the destinationphysical storage node 112 corresponding to data written to journal spacelogical unit 120 (e.g., in embodiments where more than one physicalstorage node 112 is placed in powersave mode).

In the event node 102 issues a read operation to data space logical unit118 for data stored in powered-down physical storage resource 112 a, incertain embodiments controller 109 may maintain physical storageresource 112 a in powersave mode and determine the data to becommunicated to node 102 in response to the read operation based on datastored on the remaining physical storage nodes 112 b-e. For example,when a read operation is made for a particular block of physical storageresource 112 a, controller 109 may first read journal space logical unit120 to determine whether the particular block was the destination of awrite that occurred after physical storage resource 112 a was placed inpowersave mode. If the particular block was the destination of such awrite, controller 109 may respond to the read operation with therelevant data stored in journal space logical unit 120. On the otherhand, if such a write has not occurred after physical storage resource112 a was placed in powersave mode, any data that existed on arrayvolume data space 114 a of physical storage resource 112 a prior toentering power-save mode may be determined based on data present onarray volume data spaces 114 b-e, because of the redundant nature ofdata space logical unit 118. Accordingly, in such a scenario, controller109 may respond to the read operation by performing a parity operationor other suitable operation with respect to the relevant data stored inarray volume data spaces 114 b-e.

Although FIG. 2 discloses a particular number of steps to be taken withrespect to method 200, it is understood that method 200 may be executedwith greater or fewer steps than those depicted in FIG. 2. In addition,although FIG. 2 discloses a certain order of steps to be taken withrespect to method 200, the steps comprising method 200 may be completedin any suitable order. Method 200 may be implemented using system 100 orany other system operable to implement method 200. In certainembodiments, method 200 may be implemented partially or fully insoftware embodied in tangible computer-readable media.

FIG. 3 illustrates a flow chart of an example method 300 for updating aphysical storage resource 112 from a powersave mode, in accordance withthe present disclosure. According to one embodiment, method 300preferably begins at step 302. As noted above, teachings of the presentdisclosure may be implemented in a variety of configurations of system100. As such, the preferred initialization point for method 300 and theorder of the steps 302-312 comprising method 300 may depend on theimplementation chosen.

At step 302, node 102, controller 109, and/or another suitable componentof system 100 may determine that one or more of the powered-downphysical storage resources 112 (e.g., physical storage resource 112 a inthe example discussed with respect to method 200) is to exit powersavemode. For example, a determination to exit a powersave mode may be madebased on a policy and/or algorithm that defines when a physical storageresource 112 is to be placed in or removed from powersave mode. In someembodiments, such a policy and/or algorithm may establish a timeschedule for placing one or more of physical storage resources 112 in apowersave mode and/or removing them from the powersave mode. In additionor alternatively, a policy and/or algorithm may dictate that a physicalstorage resource 112 is to be removed from powersave mode when data andinformation relating to the particular physical storage resource 112 andstored in journal space logical unit 120 has reached a threshold (e.g.,a certain percentage of the available storage space of journal spacelogical unit 120). As a further example, a physical storage resource 112may be removed from power save mode in the event of a failure of anotherphysical storage resource 112 in the storage array 110.

At step 304, in response to a determination that physical storageresource 112 a is to exit powersave mode, controller 109 may removephysical storage resource 112 a from powersave mode (e.g., by returningpower to it or issuing a command or message to exit a standby or sleepstate).

At step 306, controller 109 and/or another suitable component of system100 may update the powered-up physical storage resource 112 a based oninformation and/or data stored in journal space logical unit 120. Forexample, physical storage resource 112 a may be updated based onjournaled writes made to journal space logical unit 120 which includethe write data along with destination information associated with thewrite data. At step 308, controller 109 and/or another suitablecomponent of system 100 may deactivate journal space logical unit 120after updating physical storage resource 112 a.

At step 310, controller 109 and/or another component of system 100 maydetermine whether the powersave mode was exited because of a failure ofa physical storage resource 112. If the powersave mode was not exitedbecause of a failure of a physical storage resource 112, method 300 mayend. However, if the powersave mode was exited because of a failure of aphysical storage resource 112, data space logical unit 118 may be in adegraded state and the failed physical drive may need to be replaced andrebuilt. In such a case, method 310 may proceed to step 312.

At step 312, controller 109 and/or another suitable component of system100 may rebuild array volume space 114 of failed physical storageresource 112 from array volume data spaces 114 of the remaining physicalstorage resources 112, using any suitable data rebuild process.

Although FIG. 3 discloses a particular number of steps to be taken withrespect to method 300, it is understood that method 300 may be executedwith greater or fewer steps than those depicted in FIG. 3. In addition,although FIG. 3 discloses a certain order of steps to be taken withrespect to method 300, the steps comprising method 300 may be completedin any suitable order. Method 300 may be implemented using system 100 orany other system operable to implement method 300. In certainembodiments, method 300 may be implemented partially or fully insoftware embodied in tangible computer-readable media.

Although the methods set forth above discuss a specific example wherebyphysical storage resource 112 a is placed in a powersave mode, anycombination of one or more physical storage resources 112 may be placedin a powersave mode in accordance with the systems and methodsdisclosed. For illustrative purposes only, a specific example of anembodiment wherein more than one physical storage resource 112 may beplaced in a powersave mode in one in which storage array 110 includes afour-physical storage resource RAID 10 (assume for purposes of thisexample that physical storage resource 112 e is not present). In thisexample, storage resources 112 a-b may be placed in a powersave modewhile journal spaces 116 c-d comprises the journal space logical unit120. The journal space logical unit 120 in this embodiment may be a RAID1.

In addition, in accordance with certain embodiments of the presentinvention, various physical storage resources 112 in storage array maybe placed in and removed from a powersave mode according to a schedulingpolicy or algorithm. For example, a manufacturer, network administrator,information technology technician, or another user may establish aschedule whereby physical storage resources 112 “take turns” beingplaced in powersave mode. As a specific example, a network administratormay establish a policy whereby storage resource 112 a is placed inpowersave mode on Monday, storage resource 112 b is placed in powersavemode on Tuesday, storage resource 112 c is placed in powersave mode onWednesday, storage resource 112 d is placed in powersave mode onThursday, storage resource 112 e is placed in powersave mode on Friday,and no storage resources are placed in powersave mode on Saturday andSunday. Under this scenario, storage resource 112 a would be placed inpowersave mode on Monday in accordance with a method similar to method200. On Tuesday, storage resource 112 a would be removed from powersavemode in accordance with a method similar to method 300, and storageresource 112 b would be placed in powersave mode on Monday in accordancewith a method similar to method 200, and so on. As another specificexample, in an embodiment whereby storage array 110 includes afour-physical storage resource RAID 10 (e.g., without physical storageresource 112 e), physical storage resources 112 a-112 b may be placed inpowersave mode on odd-numbered days, and physical storage resources 112c-112 d may be placed in powersave mode on even-numbered days.

Using the methods and systems disclosed herein, problems associatedconventional approaches to management of power consumption in a storagearray may be reduced or eliminated. For example, because the methods andsystems disclosed may allow for reduced power consumption in redundantstorage arrays by placing one or more physical storage resources in apowersave mode while maintaining the capability to recover from a singlephysical storage resource failure without data loss.

In addition, the power savings achieved in certain embodiments maysignificantly outweigh the associated loss of storage capacity required.For example, in a five-physical storage resource RAID 5 logical unit, auser may desire to implement a journal space logical unit that canredundantly store 10% of the capacity of the physical storage resource112 to be powered down. Such an implementation would require eachjournal space 116 to use approximately 3⅓% of the storage space of itsassociated physical storage resource 112 (e.g., if physical storageresource 112 a is to be placed in powersave, each of journal spaces 116would need to be 3⅓% of the storage space of a physical storage resource112 in order to store 10% of the capacity of physical storage resource112 a while also maintaining redundancy). Thus, in this particularexample, a 20% power consumption reduction may be achieved whilesacrificing only 3⅓% in storage capacity.

Another potential advantage of certain embodiments disclosed herein isthat by reducing the amount of time each physical storage resource 112in a storage array is fully powered, the mean time before failure (MTBF)of each individual physical storage resource may increase, particularlyin embodiments were physical storage resources 112 are placed inpowersave mode in a round-robin fashion. Any increase of MTBF forindividual physical storage resources 112 may not only decrease theoccurrence of physical storage resource failures necessitating therebuilds thereof, but may also increase the MTBF for the redundantstorage array 110 itself, thus providing increased data integrity.

Although the present disclosure has been described in detail, it shouldbe understood that various changes, substitutions, and alterations canbe made hereto without departing from the spirit and the scope of theinvention as defined by the appended claims.

What is claimed is:
 1. A method for managing a storage array,comprising: segmenting each of a plurality of physical storage resourcesinto a first storage area and a second storage area; activating a firstlogical unit including each first storage area of the plurality ofphysical storage resources; placing at least one designated physicalresource of the plurality of physical storage resources in a powersavemode; activating a second logical unit including the second storageareas of some of the plurality of physical storage resources but not theat least one designated physical storage resource, wherein neither thesecond logical unit nor any virtual resource comprising the secondlogical unit is presented as a logical unit to any node communicativelycoupled to the plurality of physical storage resources; and storing dataassociated with a write operation intended for the at least onedesignated physical storage resource to the second logical unit.
 2. Amethod according to claim 1, wherein at least one of the first logicalunit and the second logical unit is a redundant storage array.
 3. Amethod according to claim 2, wherein the redundant storage array is aredundant array of inexpensive disks (RAID).
 4. A method according toclaim 3, wherein each of the first logical unit and the second logicalunit is a RAID of the same RAID level.
 5. A method according to claim 3,wherein each of the first logical unit and the second logical unit is aRAID, and the first logical unit and the second logical unit are of adifferent RAID level.
 6. A method according to claim 1, wherein storingdata associated with the write operation includes storing informationassociated with the destination of the data to be written.
 7. A methodaccording to claim 1, further comprising presenting the first logicalunit to a node communicatively coupled to the plurality of physicalstorage resources as a single logical unit.
 8. A method according toclaim 1, further comprising: removing the at least one designatedphysical storage resource from the powersave mode; and updating the atleast one designated physical storage resource based on informationstored in the second logical unit.
 9. A system for managing a storagearray, comprising: a plurality of physical storage resources; and adevice communicatively coupled to the plurality of storage resources,the device configured to: segment each of the plurality of physicalstorage resources into a first storage area and a second storage area;activate a first logical unit including each first storage area of theplurality of physical storage resources; place at least one designatedphysical resource of the plurality of physical storage resources in apowersave mode; activate a second logical unit including the secondstorage areas of some of the plurality of physical storage resources butnot the at least one designated physical storage resource, such thatneither the second logical unit nor any virtual resource comprising thesecond logical unit is presented as a logical unit to any nodecommunicatively coupled to the plurality of physical storage resources;and store data associated with a write operation intended for the atleast one designated physical storage resource to the second logicalunit.
 10. A system according to claim 9, wherein at least one of thefirst logical unit and the second logical unit is a redundant storagearray.
 11. A system according to claim 10, wherein the redundant storagearray is a redundant array of inexpensive disks (RAID).
 12. A systemaccording to claim 11, wherein each of the first logical unit and thesecond logical unit is a RAID of the same RAID level.
 13. A systemaccording to claim 11, wherein each of the first logical unit and thesecond logical unit is a RAID, and the first logical unit and the secondlogical unit are of a different RAID level.
 14. A system according toclaim 9, the device further configured to store information associatedwith the destination of the data to be written.
 15. A system accordingto claim 9, the device further configured to present the first logicalunit to a node communicatively coupled to the plurality of physicalstorage resources as a single logical unit.
 16. A system according toclaim 9, the device further operable to: remove the at least onedesignated physical storage resource from the powersave mode; and updatethe at least one designated physical storage resource based oninformation stored in the second logical unit.
 17. A system according toclaim 9, wherein the device comprises a controller.
 18. A program ofinstructions embodied in a non-transitory computer-readable medium andoperable to, when executed: segment each of a plurality of physicalstorage resources into a first storage area and a second storage area;activate a first logical unit including each first storage area of theplurality of physical storage resources; place at least one designatedphysical resource of the plurality of physical storage resources in apowersave mode; activate a second logical unit including the secondstorage areas of some of the plurality of physical storage resources butnot the at least one designated physical storage resources, such thatneither the second logical unit nor any virtual resource comprising thesecond logical unit is presented as a logical unit to any nodecommunicatively coupled to the plurality of physical storage resources;and store data associated with a write operation intended for the atleast one designated physical storage resource to the second logicalunit.
 19. A program of instructions according to claim 18, furtheroperable to: remove the at least one designated physical storageresource from the powersave mode; and update the at least one designatedphysical storage resource based on information stored in the secondlogical unit.